The invention concerns a two-part protector for a pipe end provided with an external thread or internal thread, wherein a substantially cylindrical thread part of plastic material covers the thread of the pipe end and a sleeve of metal that is also substantially cylindrical supports the threaded part rearwardly and wherein the threaded part and the sleeve engage one another lockingly by locking projections and locking cutouts. The invention concerns moreover a method for producing such a protector. Such protectors are used in particular for transporting and storing pipes with threads and other sensitive couplings at the pipe ends. Primarily, pipes for drill strings are to be protected with respect to tough manipulation and storage conditions at their sensitive thread areas. The threads can be external threads but also, for example, in case of the ends of socket pipes, internal threads. Both must be protected from damage, deformations, and soiling.
As an immediate cover of such a threads primarily threaded parts of plastic material are suitable that, with regard to their manufacture, can be easily adjusted to different threads and primarily in case of impacts at the ends are less hard and also less strong compared to the threads of the pipes so that they absorb loads and do not transmit them onto the threaded part. This is an immediate protective thread cover. However, in order for such protectors to be able to withstand also severe loads, such protectors are often additionally provided with a cylindrical sleeve of metal, preferably steel, that for protecting an external thread are arranged so as to surround the threaded part of plastic material or, for protecting an internal thread, cover the internal side of the threaded part of plastic material. In both cases the threaded part with its leading end (thread side) contacts the thread and at its rear is supported by the metal sleeve. Both parts of the protector are coupled lockingly in a well-known way. However, in this connection the problem is often encountered that the much harder and stronger metal sleeve damages integrally formed locking projections on the threaded parts. As a result of this and also because of precautionary tolerances in regard to the seat of the locking means there is the risk that the sleeve relative to the threaded part will become detached or as a result of movement play during transport damage is caused on the threaded part made of plastics. The locking seat between sleeve and threaded part must be ensured even under extreme temperatures wherein in particular the different thermal expansion of metal (steel) and plastic material (threaded part) especially causes difficulties. Problems with the proper locking seat between threaded part and sleeve also have an effect on the possibility of unscrewing the protector from the thread or screwing it again onto the thread when the screwing action is realized through the metal sleeve.
Object of the invention is therefore to provide a two-part protector where the sleeve and the threaded part can be plugged into one another fixedly and with little play without the threaded part becoming damaged in the process and in which also an excellent connection between sleeve and threaded part ensures a problem-free manipulation when screwing on or unscrewing it, even in case of use under extreme temperature conditions.